Conventionally, a heater which employs a base material made of metal such as stainless steel or aluminum alloy has been used in semiconductor-producing/examining devices such as an etching device and a chemical vapor phase growth device.
However, such a heater made of metal has the following problems.
The thickness of its ceramic substrate must be as thick as on the order of 15 mm since the heater is made of metal. This is because, in a thin metal plate, a warp, a strain and the like are generated due to thermal expansion resulting from heating, so that a semiconductor wafer placed on the metal plate is damaged or inclined. However, if the thickness of the ceramic substrate is made thick, a problem that the heater becomes heavy and bulky arises.
Heating temperature is controlled by changing the voltage or current amount applied to heating elements. However, since the metal plate is large, the temperature of the ceramic substrate does not follow the change in the voltage or current amount promptly. Thus, a problem that the temperature is not easily controlled is caused.
The heater made of metal also has a problem that corrosion resistance against corrosive gas is poor since the heater is made of metal.
Dealing with the problems, JP Kokai Hei 11-40330 discloses a ceramic heater wherein a nitride ceramic or a carbide ceramic, which has a high thermal conductivity and a great strength, is used in place of the metal heater, and heating elements formed by sintering metal particles are provided on the surface of a ceramic substrate made of this ceramic.
In such a heater, a warp, a strain or the like is not easily generated in its ceramic substrate even if the heater thermally expands at the time of being heated. Thus, the temperature-following character thereof under a change in applied voltage or current amount is also good.